Can somebody enlighten me on the black "code plug" on the back of the cruise control unit? As far as I understand, the control unit (the big silver box) is shared across various models, whereas the black plug is more model specific (the older control units don't have a code plug on the back).

For my car (1989 230CE unusual in the us, I know) there is a number of control units available (A0235452132 A0165457732 A0145454032 A0055450532) but there is only one code plug (007 545 0632) and it is hard to find, i.e. expensive.

I have the usual problem. Cruise engages sometimes, holds for a while, but cuts out eventually. Sometimes it does not work at all.

I know bad soldering in the control unit is a common problem. Could it also be the control plug, or could I reasonably think the plug is ok and order a correct control unit with a different plug and reuse my old plug?

Thought?

As far as I remember the coding plug only contains a couple of resistors and is unlikely causing problems. A good Mercedes shop will have a cruise control tester and a proper diagnose is likely cheaper than throwing parts at it.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

Thanks! True, fair point. However with Norwegian Mercedes-labour prices, a diagnosis will probably be as expensive as a good control unit. Especially if I end up needing one after all...

Try this out:
http://www.cruisecontrolrepair.com/new-page

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1990 190E 3.0L

Also, check your tyre sizes and inflation pressures - the rolling diameter must be within a certain tolerance or the system will disengage when the rotational speed differential reaches a certain point.

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Robert Fini

'12 ML350 BlueTec, 87k
'06 E320CDI, 270k
'05 T1N Sprinter 2500/Pleasure-Way Plateau TS, 69k
'97 C36AMG, 313k (son's)
'94 E320T, 249k
'93 190E Sportline LE, 168k (daughter's)
'84 190E-2.3/5spd (Stage Rally Racer)
'66 230 W110 Sedan (Barn Find, Vintage Racer build in progress)

Erratic cruise control can also be caused by incorrect brake lamp bulbs. This may be worth checking.

Good luck with finding the plug info you seek, sorry I cannot help with that.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Thanks - however, not having ASR my car doesn't have a clue how fast my wheels are spinning - I think, but I could be wrong. Tyre size is stock and inflation pressure ok BTW.

Thanks - will check brake bulbs!

I always thought it was the ABS that intervened, but I could be wrong; nevertheless, it's always good policy to check the basics first. Is there a pattern to the failure? My first '94 E320T would cut out pretty regularly on the highway and wouldn't reactivate until I cycled the power; unfortunately, the car was called upon to save my wife's life before I could fully diagnose the problem. Try cleaning the ABS sensors out at the wheel hubs to see if that makes a difference.

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Robert Fini

'12 ML350 BlueTec, 87k
'06 E320CDI, 270k
'05 T1N Sprinter 2500/Pleasure-Way Plateau TS, 69k
'97 C36AMG, 313k (son's)
'94 E320T, 249k
'93 190E Sportline LE, 168k (daughter's)
'84 190E-2.3/5spd (Stage Rally Racer)
'66 230 W110 Sedan (Barn Find, Vintage Racer build in progress)

The code plug is just a bunch of resisters. I think it is used for speed sensitivity to maintain speed and nothing else. I find any plug would work. It is likely the control unit itself is faulty if it cuts off sometimes. I picked up a few 190E cruise units from junk yard and they work perfectly on all my diesel.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Those old electronics will all have swollen capacitors and such that are totally out of specification now. Either you rebuild the unit with new electronics or just forget about cruise control. a new rebuilt unit is probably ridiculously expensive. I drove 2000km in my mine without cruise and it wasn't bad. These cars are so comfortable you don't even need it.

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1987 300E

Thanks - I will replace all the 6 old capasitors and see what happens. Or else, junk yards or rather ebay, seem to be the way to go!

True - its just that it gives the proper MB luxury feeling. I cant help smiling from ear to ear when it (sometimes) engages on the highway in my 31 years old w124